libc/glibc: add multilib-cacpable backend

For mutlilib, the C library must be built once for each variants.
Special care must be taken to put the resulting libraries in
the proper places.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Alpha specific configuration file

## select ARCH_SUPPORTS_32

## select ARCH_DEFAULT_32

## select ARCH_USE_MMU

## select ARCH_SUPPORTS_WITH_CPU

## select ARCH_SUPPORTS_WITH_TUNE

##

## help The Alpha architecture.